JPS6233656B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a device for vertically and horizontally moving an objective lens of an optical pickup device, and in particular, a tracking drive unit and a focus drive unit are disposed parallel to and on the same line with respect to a disk, and the objective lens is focus-driven. The present invention relates to a device for vertically and horizontally moving an objective lens of an optical pickup device, which is arranged to be shifted from the center position of the disk in the radial inner circumferential direction of the disk.

An example of focus and tracking control in a conventional optical pickup device is shown in Figures 1 and 2. According to these, focus (Z-axis direction) control is performed by voice coil electromagnetic drive, and tracking (X-axis direction) control is performed by linear drive. This is done by electromagnetic driving of a motor, and the object to be driven is the objective lens 1 in both cases. That is, a cylindrical permanent magnet 4 to which the objective lens 1 is fixed is mounted on a parallel plate spring 3 for tracking mounted inside the lens barrel 2, and a voice coil 5 is provided around the middle of the lens barrel 2, protruding from the middle part of the lens barrel 2. Cylindrical permanent magnet 4, voice coil 5
are arranged in a linear motor electromagnetic drive unit 7 installed inside the upper part of the housing cylinder 6 and a voice coil electromagnetic drive unit 8 installed inside the middle part of the housing cylinder 6, respectively, and have a circular hole in the center. . Parallel leaf spring for focus 9
is used to hold the lens barrel 2 inside the storage barrel 6, and move the objective lens 1 in the Z-axis direction or the It is meant to be moved. In this way, the tracking drive section and the focus drive section are perpendicular to the disk.
arranged in tiers.

In this prior art, it is desirable that the tracking parallel plate spring 3 has a small spring constant in order to widen the range of tracking operation, and it is also necessary to have a somewhat large spring constant in order to be able to stand on its own. Furthermore, metal is preferable because it is not affected by temperature changes. Taking all of the above into consideration, long metal leaf springs are generally used. Accordingly, the size _H1 of the optical pickup device in the Z-axis direction becomes large, which poses a problem in that the optical pickup device becomes large and heavy.

In addition, when the housing of the disk rotation drive motor and the pickup body are on the same side, when picking up the inner circumference of the disk, it is preferable that the separation distance R ₁ between the optical axis and the outer surface of the pickup body in the disk radial direction be as small as possible. , voice coil 5 and voice coil electromagnetic drive section 8
Since the focus drive section and the objective lens 1 are arranged concentrically, there is a problem in that the size cannot be reduced beyond a certain level.

The present invention has been made by focusing on the problems of the prior art, and is made by arranging the tracking drive section and the focus drive section parallel to and on the same line with respect to the disk, and placing the objective lens at the center position of the focus drive section. It is an object of the present invention to solve the above-mentioned problem by arranging the discs so as to be shifted further in the radial direction of the inner circumference of the disk.

The present invention will be explained below based on the drawings.

FIG. 3 is an exploded perspective view showing an embodiment of the present invention.

First, the structure will be explained. Reference numeral 11 is a focus drive permanent magnet, which has a cylindrical shape. The focus drive unit permanent magnet 11 is a ring-shaped permanent magnet piece 11A.
and a ring-shaped magnetic piece 11B larger than the permanent magnet piece 11A fixed to the upper surface of the permanent magnet piece 11A.
and a pipe flange-shaped magnetic piece 11C fixed to the lower surface of the permanent magnet piece 11A.
A gap 11D is formed between 1B and 11C. A focus drive permanent magnet 11 is fixed to an outer frame 12. 13 is a vertically moving part, which is a cylinder. A focus control round coil 14 is disposed in the gap 11D of the focus drive permanent magnet 11 in the middle of the vertical moving part 13, and four arms radially extend from the circumferential surface of the upper and lower ends. 13A is provided protrudingly, and the tracking movement direction (X
A through hole 13B is bored parallel to the axial direction). The arm 13A forms an angle of 45 degrees with the tracking movement direction (X-axis direction), and its length is larger than the radius of the focus drive permanent magnet 11. Further, the distance between the through holes 13B is greater than the height of the focus drive permanent magnet 11. Reference numeral 15 designates parallel plate springs for tracking, which are attached to left and right upper and lower arms 13A perpendicular to the through hole 13B. 1
6 is a shaft with a parallel plate spring 15 for tracking.
The tracking parallel plate spring 15 is fixed to the tracking parallel plate spring 15 by welding or the like through a through hole 15A and a through hole 13B formed at the top and bottom of the center. A lens barrel 1A on which the objective lens 1 is mounted is fixed to the left end of the shaft 16. In this way, objective lens 1
As shown in FIG. 4, the magnet 1 is disposed offset in the radial inner circumferential direction of the disk D from the center position of the focus drive section consisting of the focus drive permanent magnet 11 and the focus control round coil 14. Therefore, the separation distance R ₂ between the optical axis and the outer surface of the pickup body
can be made smaller compared to the conventional technology. Shaft 16
A rectangular coil 17 for tracking control is fixed to the right end. Reference numeral 18 denotes a tracking drive permanent magnet, which includes two permanent magnet pieces 18A and 18B, a flat T-shaped magnetic piece 18C which is clamped between the S poles of the two permanent magnet pieces 18A and 18B, and two permanent magnet pieces 18A and 18B. It is composed of magnetic pieces 18D and 18E having a plane L-shape and a plane 'shape, which are fixed to the N-pole side of the magnet piece. A gap 18F is formed between the magnetic piece 18C and the magnetic piece 18D and between the magnetic piece 18C and the magnetic piece 18E. The tracking drive permanent magnet 18 is fixed to the outer frame 12 and
A rectangular coil 17 for tracking control is inserted into F. In this way, the tracking drive permanent magnet 1
8 and a rectangular coil 17 for tracking control is arranged parallel to the disk D and on the same line as the focus drive section. Therefore, the size of the optical pickup device in the Z-axis direction
H ₂ becomes smaller, and the optical pickup device can be made thinner. Reference numeral 19 denotes a focus parallel plate spring, which is inserted between the outer frame 12 and the upper surface 13C of the vertically moving section 13 and between the outer frame 12 and the lower surface 13D of the vertically moving section 13 to elastically support the vertically moving section 13. . The height of the tracking control rectangular coil 17 is as follows:
The square coil 17 for tracking control is set so as not to come into contact with the magnetic piece 18C of the permanent magnet for tracking drive during focus movement (Z-axis direction).

Next, the effect will be explained. When the focus error signal or the tracking error signal is zero, no current flows through the focus control round coil 14 or the tracking control square coil 17, and the objective lens 1 remains stationary at a predetermined position. If there is a focus error signal now, a current flows through the focus control round coil 14. Since the direction of this current and the direction of the magnetic flux from the focus drive permanent magnet 11 are perpendicular to each other, the focus control round coil 14 receives a force in the vertical direction (Z-axis direction) based on Fleming's left hand rule. The focus control round coil 14 is integrated with the vertical moving section 13 and is elastically supported by the focus parallel plate spring 19, so that it moves in the vertical direction (Z-axis direction). Therefore, the focus control round coil 1
The objective lens 1, which is integrated with the objective lens 4 via the vertical moving part 13 and the shaft 16, also moves in the vertical direction (Z-axis direction). Note that the direction and amount of movement are determined by the direction and magnitude of the current flowing through the focus control round coil 14. Next, when there is a tracking error signal, a current flows through the tracking control rectangular coil 17. Since the direction of this current and the direction of the magnetic flux from the tracking drive permanent magnet 18 are perpendicular to each other, the tracking control rectangular coil 17 receives a force in the left-right direction (X-axis direction) based on Fleming's left-hand rule. The square coil 17 for tracking control is integrated with the shaft 16 and the parallel plate spring 15 for tracking, and is controlled in the left-right direction (X
Since it is elastically supported in the axial direction), it moves in the left-right direction (X-axis direction). Therefore, the objective lens 1, which is integrated through the tracking control rectangular coil 17 and the shaft 16, also moves in the left-right direction (X
axial direction). The direction and amount of movement are determined by the direction and magnitude of the current flowing through the tracking control rectangular coil 17. Note that the focus error signal and the tracking error signal are
As shown in the figure, the laser beam from the semiconductor laser 20 is passed through the collimator lens 21 and the polarizing beam splitter 2.
2. Guide the light reflected from the disk D to the 1/4 wavelength plate 23, the 90° deflection mirror 24, and the objective lens 1, and return the reflected light from the disk D in the reverse order to the polarizing beam splitter 22, deflect it by 90°, and a light shielding plate (not shown); It is obtained by guiding the light through a converging lens to a 4-split sensor.

As explained above, the present invention arranges the tracking drive section and the focus drive section parallel to the disk and on the same line, and also shifts the objective lens from the center position of the focus drive section in the direction of the inner radius of the disk. By arranging the optical pickup device, it is possible to make the optical pickup device thinner.
This provides the effect that the distance between the optical axis and the outer surface of the optical pickup device can be reduced.

[Brief explanation of the drawing]

Fig. 1 is a sectional view of the prior art, Fig. 2 is an exploded perspective view of a tracking drive unit of the prior art, Fig. 3 is an exploded perspective view showing an embodiment of the present invention, and Fig. 4 is an exploded perspective view of a tracking drive unit of the prior art. It is a schematic sectional view taken along line A'-A in FIG. 3. 1... Objective lens, 2... Lens barrel, 3... Parallel leaf spring for tracking, 4... Cylindrical permanent magnet, 5... Voice coil, 6... Storage tube, 7...
Linear motor electromagnetic drive section, 8...Voice coil electromagnetic drive section, 9...Parallel plate spring for focus, 10
... Coil, 11 ... Permanent magnet for focus drive, 12 ... Outer frame, 13 ... Vertical moving part, 14 ...
...Round coil for focus control, 15...Parallel plate spring for tracking, 16...Shaft, 17...
... Square coil for tracking control, 18 ... Permanent magnet for tracking drive, 19 ... Parallel plate spring for focusing, 20 ... Semiconductor laser, 21 ... Collimator lens, 22 ... Polarizing beam splitter, 23 ... 1/ 4 wavelength plate, 24...90° deflection mirror.

Claims (1)

[Claims] 1 A ring-shaped focus drive permanent magnet consisting of a permanent magnet piece and a magnetic piece fixed to an outer frame, and a focus control round coil arranged in a gap between the focus drive permanent magnet are protruded around the circumference. A vertical moving part has four arms protruding radially from the circumferential surface of the upper and lower ends, and has a through hole bored in the upper and lower ends parallel to the tracking movement direction, and a vertical moving part on the left and right that is orthogonal to the through hole. a tracking parallel plate spring attached to the arm; a through hole drilled above and below the center of the tracking parallel plate spring; and two shafts passing through the through hole and fixed to the tracking parallel plate spring; A lens barrel to which an objective lens is fixed fixed to the left end of the shaft, a rectangular coil for tracking control fixed to the right end of the shaft, and a part of the rectangular coil for tracking control is inserted into a hollow part of the rectangular coil for tracking control. A tracking drive permanent magnet consisting of a permanent magnet piece and a magnetic piece fixed to an outer frame, and a parallel focus plate inserted between the outer frame and the upper and lower surfaces of the vertically moving part to elastically support the vertically moving part. A device for moving the objective lens of an optical pickup device up and down and left and right, consisting of a spring.